This can be actually be found in historical reenactment troupes: "whites" reenactors are often royalists IRL and "blues" reenactors are well... a bit more normal ;). But this is not historical reenactment: in LARPs people play usually fictional characters with specific goals, there's a secret plot that may have nothing to do with history, and most of the action is improvised. The setting is historical but the same people may very well play in a Starship Troopers LARP or a Lord of the Rings LARP next month.